The two 4,5 MW heat pumps are using the water of lake Leman as a heat source. Extracting the water at a flow of approximately 260 l/second, with a constant temperature of 6 – 7°C, the heat pumps are able to supply heat in two district heating networks and a storage tank.
The heat pumps work at full capacity even when there is lower demand from the district heating systems, by filling the storage tank. The storage option has the role of limiting the start-ups of the heat pumps, thus limiting their mechanical wear. The heat pumps work only when the temperature is below 16°C, by supplying 28 to 65°C in the average temperature network and 26 to 50°C in the low temperature network. However, for the peak loads, when outside temperatures are very low, the heat pumps are supported by two gas turbines. Cooling capacities, for the laboratories and ventilation, are ensured by the same heat pumps. The refrigerant used is NH3 and the COP achieved is 4,8.